To disable Google Assistant's weather forecasts, go to the Google app on your Android device: Long press on the home screen to open the app drawer, then select the Google app. Tap on the menu button (three horizontal lines), scroll down to the 'Settings' section and tap on it. Select 'Account' and then 'Google Assistance'. Under 'Additional settings', toggle off the switch next for 'Enable Google Assistant to display weather forecasts'. Alternatively, you can also go to your Android device's Settings app, select 'Apps & notifications', find the Google app, select it, and toggle off the 'Show weather' option. On iOS devices, open the Google app, tap on the menu button (three horizontal lines), select 'Settings', and then turn off 'Show weather'.